Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
ve cac » va cac, vien cac
va dau » va dao
ca dan » cac dan, ca dao
ca dau » ca dao, cp dau, ca cau
ca sau » ca san

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang cao hoi. hieu ve cac tuc ((va dau) or (ca dan)) ((ca dau) OR (ca sau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang cao hoi. hieu ve cac tuc ((va dau) OR (ca dan)) ((ca dau) OR (ca sau)) tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang cao hoi. hieu ve cac tuc ((va dau) or (ca dan)) ((ca dau) OR (ca sau)) tren*".